flowerhorns typically know if a batch is no good. Sometimes if it's their first time it's due to inexperience and they will eventually learn how to produce properly. It's trial and error on their part. ZZ strain fh's are fertile at a very young age compared to kamfas.
like someone said, the female should be smaller than the male or you're asking for trouble. I would keep them divided like someone said with a flat pot under the divider on both sides to prevent the lip locking if it's aggression.
use the methods people are providing, that usually helps when asking for help =D
